1. Technical Field
This invention relates generally to dynamic oil seals of the type for creating a fluid tight seal between a rotating shaft and a housing.
2. Related Art
Dynamic radial shaft oil seals are designed to have a so-called “oil-side” of the seal and an “air-side.” These designations pertain to the orientation of the seal when installed, with the oil-side facing the interior of the housing and in communication with the oil, whereas the air-side faces outwardly and is exposed to the air.
During use, it is desirable to keep dust and other contaminants on the air-side of the seal while maintaining lubrication on the oil-side of the seal. It is known to incorporate spiral grooves in a seal lip to pump lubrication back to the oil-side of the seal, however, these grooves do not act to keep out dust or other contaminants. As a matter of fact, if dust or contamination enters the grooves, it will tend to be pumped along with lubrication to the oil-side of the seal. This has undesirable affects on the seal, and ultimately reduces the useful life of the seal and possible bearings or other components that the seal is protecting.
Further, it is known to incorporate spiral grooves in a seal lip to keep dust and contamination on the air-side of the seal, however, these grooves do not act to maintain lubrication on the oil-side of the seal. As a matter of fact, if lubrication enters the grooves, it will tend to be pumped outwardly to the air-side of the seal, thereby depleting the lubrication within the seal. This has undesirable affects on the seal, and ultimately reduces the useful life of the seal and possible bearings or other components that the seal is protecting.